Small floppy disk drive units are in common use today in microcomputer systems sold for both business and personal use. Because the disk drives are complex electromechanical devices which must perform with precision positioning and timing to achieve reliable operation, the disk drives often are the least reliable component of the computer system. Consequently, original equipment manufacturers (OEMs) of computer systems routinely perform receiving inspection tests on purchased disk drives to verify the quality and compatibility of the drive units. The incoming inspection procedure may also include adjustments to specifications more stringent than those advertised by the disk drive manufacturer. In addition to the testing and adjustment of disk drives by manufacturers, the servicing of existing disk drives also requires checking of performance criteria and adjustments of the unit where possible to meet specifications.
The testing systems presently used on disk drives may be classified into three general categories: exercisers, testers, and analyzers.
Exercisers are the most basic type of test equipment and usually simply provide the operator with switches by which the disk drive can be controlled, for example, by turning the motor on and off, selecting a track, reading, writing, etc. Much experience and skill is required on the part of the operator to properly perform the inspection and adjustment of the drives using this type of equipment.
Drive testers provide somewhat greater automation of the test procedure by using a controller which controls the operation of the drive unit in the proper manner for each test. The operator must still enter relevant test information (e.g., track number, type of data to write, test to perform, etc.). The actual analysis of the test results and the comparison of the results to the drive specifications is not done automatically. These testers spare the operator from the basic task of controlling the disk drive unit but the actual measurements and decisions as to the satisfactory performance of the drive must still be made by the operator.
Disk drive analyzers provide more completely automated drive measurement systems, and are capable of complete disk drive testing without additional equipment and with a high degree of automation. Some existing analyzers require the operator to select tests while others will automatically find the shortest testing procedure for a given situation. Such equipment is generally capable of automatically comparing the drive specifications to the measured results and indicating to the operator whether the test has been passed or failed.
While existing disk drive analyzers provide substantial automation of many disk drive test procedures, they are generally limited in the manner in which test results are communicated to the operator. Many tests results are reported to the operator in the form of a pass-fail indication or alphanumeric data, which gives little direct information to the operator as to how close the machine is to the specification boundary between acceptable and unacceptable performance. In particular, where the operator must adjust the drive to bring it into specification, the operator may have difficulty gauging the effect of his adjustments from the alphanumeric data displayed to him. Other analog tests of the drive's mechanical movement and timing result in an oscilloscope wave form being presented to the operator which must be analyzed by him, thus making such tests prone to operator errors.